Support for a Biological Imaging Core (B) is requested in this competitive renewal of the PPG. This new and expanded Core reflects the requirement for new modalities of light and electron microscopic analysis of cells and tissues that will be examined by investigators in this PPG. Specifically, the Image Analysis Facility will provide technical and scientific support in three areas. First, the facility will continue to provide high quality electron microscopic localization of antigens using postembedding techniques (frozen thin section immunogold electron microscopy and immunogold localizations on resin embedded material) as well as preembedding techniques. Technical support will be provided by a full-time EM technician who is presently working in this Core. Second, the core will provide technical help with the processing of materials for light microscopic immunocytochemistry. Tissue sections or whole mounts of cells will be examined using a conventional epifluorescence light microscope that is part of the Core. In addition, members of the PPG will be able to analyze their specimens with a BioRad MRC 600 laser scanning confocal light microscope which provides superior spatial resolution especially of thick specimens and allows for sophisticated double label pseudo color image gathering. The core also supports 3-D image analysis and reconstruction using VoxelView software and a Silicon Graphics Iris workstation that is available to investigators via this Core. Technical as well as scientific expertise is available in this field through Core B. Third, the Core will provide technical support in the preparation and photography of conventional thin sections that are required for analyzing phenotypes of cells and composition of cell fractions in several of the projects. Facilities also of interest to investigators in the PPG that are associated with Core B consist of darkroom facilities for preparation of working photographic prints and the services of the Cell Biology Department's graphics specialist who will assist in the preparation of publication prints and graphics for members of the PPG. Fourth, an important responsibility of the professional staff will be training, supervision and quality control of primarily new students and postdoctoral fellows who will participate in PPG projects. Dr. Jamieson will be overall director of this Core. He will be assisted by Drs. Paul Webster and Ann Cornell-Bell in the scientific feasibility assessment of projects using the Core. Dr. Webster's area of expertise is in the preparation and analysis of material for EM immunocytochemistry. Dr. Ann Cornell-Bell will provide scientific guidance in the use of confocal laser scanning LM and 3-D image reconstruction. All three professionals will be available for consultation, advice and collaboration with members of the PPG.